We need to set aside factory HP ratings vs dyno ratings, as the factory #s were without accessories, optimized, and influenced by marketing.
Obviously, an ACCURATE dyno tells the real tale, but most of us have seen "happy" dyno #s.
The issue, I suspect, is if a stroked Poly will have the torque to move an early B wagon along on the street while being cost-effective.
Max cost-effectiveness is probably a later 360/5.9, maybe even an EFI deal.
Like I said, depends on how stock-appearing the OP wants.
My stock, tired Polys moved my '63 & '64 stick wagons along pretty well.
Neither (obviously) was at all fast, but pretty adequate, and they were both tired, as in mildly smokin' tired, when I got them.
IIRC, Polyspheric's book had a 400-ish HP stroker recipe, but I'm assuming the OP just wants a street cruiser (torque).

I'll throw this out there: look how hard Dizuster's '62 Savoy runs with a simple turbo 360 recipe...